Resilient retainer for excavating tooth



June 6, 1967 G. A. PETERSEN RESILIENT RETAINER FOR EXCAVATING TOOTHFiled. Nov. 25, 1964 6 Sheets-Sheet l INVENTOR. GERALD A. PETERSEN A 7'TORNEV June 6, 1967 G. A. PETERSEN 3,323,235

RESILIENT RETAINER FOR EXCAVATING TOOTH Filed Nov. 25, 1964 6Sheets-Sheet 2 Ill-V I A 7'? II I III 'fe'lllll' BY A T TOR/IE V FiledNov. 25, 1964 6 Sheets-Sheet 5 F/G /5 3r INVENTOR. GER/4L0 A. PETERSEN A7' TORNEV June 6, 1967 e. A. PETERSEN RESILIENT RETAINER FOR EXCAVATINGTOOTH 6 Sheets-Sheet Filed Nov. 2 3, 1964 FIG- 20 24d -44d l d avd #2 7dINVENTOR.

GERALD A. PETERSEN Id 43d 9 June 6, 1967 e. A. PETERSEN 3,323,

RESILIENT RETAINER FOR EXCAVATING TOOTH Filed Nov. 23, 1964 6Sheets-Sheet 5 FIG- 2/ INVENTOR. GER/44D A. PETE PSEA/ A 7" TOP-WE VJune 6, 1967 G. A. PETERSEN 3,323,235

RESILIENT RETAINER FOR EXCAVATING TOOTH Filed Nov. 25, 1964 6Sheets-Sheet 6 44: -24: y-sa; 374 27:

I g\%/ g INVENTOR.

76g 44 GERALD A. PETERSEN 79 37g BY 32g 2 A r TOR/VEV United StatesPatent" Calif., assignor of This invention relates to a new and improvedresilient retainer for excavating tooth. Various earth-digging machinessuch as angers, trenching machines, and the like, use replaceable teethwhich are held in place by a tooth holder formed integrally or attachedto the equipment. As the teeth are worn they may be reversed to increasetheir life, they may be removed for the purpose of sharpening, or theymay be replaced when worn. Therefore, it is necessary to have a meanswhich will hold the tooth on its holder under considerable stress andwith security, and yet will permit intentional separation of the toothand holder. The present invention provides such means.

A particular advantage of the present invention is the facility withwhich the tooth may be installed and removed and the fact that nospecial tools are required for such purpose.

A still further advantage of the invention is the fact that the meanswhich secures the tooth on its holder is resilient and henceaccommodates minor variations in the construction of the tooth and theholder, thereby making close tolerances unnecessary and furtheraccommodating wear of the parts with the passage of time.

A still further feature of the invention is the provision of cooperatingmeans on the tooth and its holder to prevent the tooth from beingdisplaced from its proper position when the tooth is subjected to severestress such as striking a hard object at one corner of the tooth.

In the form of the invention hereinafter described in detail, the toothholder is formed with a pair of recesses extending rearwardly from theforward end so that the shape of the holder, as viewed in frontelevation, is substantially that of an H turned on its side. A Webextends between the top and bottom portions of the holder. The toothwhich is used with such a holder has a tapered distal portion whichperforms the digging function and a bifurcated proximal portion composedof two prongs separated from each other by a substantially rectangularslot which extends forwardly from the proximal end of the tooth. The webof the holder fits into the slot with relatively close tolerances. In apreferred form of the invention a hole is formed extending through theweb and rearwardly of the hole a pair of longitudinal grooves is formed.A resilient insert is inserted through the hole extending outwardly ofeither side of the web into the recesses between the top and bottomportions of the holder. When the prongs of the tooth are inserted in therecesses the resilient member is jammed between the web and the sideedges of the slot of the tooth. The grooves rearwardly of the holereceive the ends of the resilient insert which are bent backwardly bythe prongs of the tooth and hence the insert is jammed between theprongs and the bottom of said grooves.

In the form of the invention hereinafter described in detail, the depthof each groove is substantially less than the initial diameter of theinsert or the hole in which the insert is installed. Additionally, thewidth of the groove (i.e. in the direction extending between the top andbottom portions of the holder) is greater than the initial diameter ofthe insert or of the hole in the web. Accordingly, the resilient insertis flattened and spread in a vertical sense and this increases the areaof contact of the flattened resilient insert with the side walls of theslot of the tooth. Since the resilient insert serves as a frictionalmeans for restraining unintentional displacement of the tooth 3,323,235patented June 6, I 967 from the holder, increasing the area of contactmaterially increases the effectiveness of the holding action and thusthe present invention considerably improves the efiiciency of theretention means.

A particular advantage of the use of a wide, shallow groove andconsequent flattening of the resilient insert is the fact that thisconstruction permits the use of the principle of a resilient retainer tohold in place teeth which are considerably larger, heavier and subjectedto greater strain than have heretofore been retained by the resilientretainer principle. Thus the versatility of the retaining means isconsiderably augmented.

Accordingly, a principal feature of the present invention is the factthat bolts, metal keys and similar fastening means to secure the toothto the shank are eliminated, thereby eliminating much of the difficultyheretofore occasioned in securing the teeth to holders. The use of aresilient insert to frictionally bond the tooth to the holder inhibitsabrasive action which might eventually wear the mating parts.

A further feature of the invention is the provision of a modifiedholding means wherein the resilient insert is located in a hole whichextends through the top and/ or bottom portion of the holder rather thanthrough the web. Such an insert may be installed on one or both sides ofthe holder to engage one or both prongs on one or both surfaces of theprongs.

Still another feature of the invention is the provision of a modifiedtooth wherein the resilient insert is installed in one or more holesextending transversely through the prongs of the tooth rather thanthrough a hole in the holder. It will be understood that in somelocations and under some conditions installation of the resilient insertthrough its hole requires considerable manual dexterity or operatingconditions may interfere with the installation. Since the tooth isusually more readily portable than the holder and also is considerablymore accessible, being able to install the resilient insert through ahole in the tooth simplifies the operation.

A still further modified tooth has the holes located extending from topto bottom of the prongs rather than transversely through the prongs.Again, such a location in some instances simplifies and expedites theassembly of the insert in its holder and the eventual insertion of thetooth in the holder.

Still another feature of the invention hereinafter described in detailis the provision of a plurality of resilient inserts which cooperate tohold the tooth in its holder. By using a plurality of inserts, thesurface area which frictionally engages the two mating parts isconsiderably increased.

In connection with the modification described in the precedingparagraph, another feature of the invention is the relative location ofthe inserts, one located spaced forwardly of the other in the directionof the insertion of the tooth in its holder. Thus at the commencement ofthe insertion operation the tooth encounters only one of the pluralityof inserts, but as the insertion is continued an additional one or moreinserts are encountered. The gradual increase in frictional resistancesimplifies insertion of the tooth and yet has the advantage of moresecurely locating the tooth in its holder.

Other objects of the present invention will become apparent upon readingthe following specification and referring to the accompanying drawingsin which similar characters of reference represent corresponding partsin each of the several views.

In the drawings:

FIG. 1 is an exploded perspective view of a tooth, a portion of a holderand a resilient insert.

FIG. 2 is a side elevational view of the tooth and holder in assembledposition.

FIG. 3 is a longitudinal, horizontal, sectional view through a holderprior to installation of the tooth taken substantially along the line 33of FIG. 2.

FIG. 4 is a sectional view also taken along the line 33 of FIG. 2showing the parts in assembled position.

FIG. 5 is a transverse vertical sectional view taken substantially alongthe line 5-5 of FIG. 2.

FIG. 6 is an enlarged fragmentary sectional view taken substantiallyalong the line 6-6 of FIG. 2.

FIG. 7 is a view similar to FIG. 2, of a modification wherein the holefor location of the insert is through the top and the bottom portions ofthe holder.

FIG. 8 is a sectional view taken substantially along the line 8-8 ofFIG. 7.

FIG. 9 is a sectional view taken substantially along the line 9-9 ofFIG. 8.

FIG. 10 is a view similar to FIG. 1, of a further modified constructionwherein the holes for the insert extend horizontally transverselythrough the prongs of the tooth.

FIG. 11 is a sectional view, similar to FIG. 5 of the modification ofFIG. 10.

FIG. 12 is a sectional view taken substantially along the line 1212 ofFIG. 11.

FIG. 13 is a view similar to FIG. 1, of a further modification whereinthe holes for location of the insert extend vertically through theprongs.

FIG. 14 is a view similar to FIG. 2, of the modification of FIG. 13.

FIG. 15 is a sectional view taken substantially along the line 1515 ofFIG. 14.

FIG. 16 is a sectional view taken substantially along the line 1616 ofFIG. 15.

FIG. 17 -is a view similar to FIG. 1, of still another modificationwherein a plurality of resilient inserts is used to hold the tooth inplace of the holder.

FIG. 18 is a view similar to FIG. 2, of the modification of FIG. 17.

FIG. 19 is a sectional view taken substantially along the line 19-19 ofFIG. 18.

FIG. 20 is a sectional view taken substantially along the line EAL-21)of FIG. 18.

FIGS. 21 to 24 are views similar to FIGS. 1, 2, 5 and 4, respectively,of a further modification.

FIGS. 25 to 27 are views similar to FIGS. 10 to 12, respectively, ofanother modification.

FIGS. 28 to 30 are views similar to FIGS. 13, 15 and 16, respectively,of another modification.

The present invention provides a detachable retention means for'securinga tooth 11 to a tooth holder 12 which may be formed integrally with orsuitably secured to earth-digging equipment, the attachment involvingthe use of a resilient insert 13.

In a preferred form of the invention, the tooth 11 has forwardlyconverging top and bottom distal surfaces 16, 1'7, terminating in atransverse, blunt, forward edge 18. Preferably, the side edges 19 of thetooth are vertical and parallel.

The proximal end of the form of tooth 11 herein illustrated isbifurcated by means of a slot 21 which extends forwardly from theproximal end of the tooth and terminates in a vertical forward end 22.Preferably, the side walls 23 of the slot are vertical and parallel. Theslot 21 divides the proximal end of the tooth into two prongs 24 whichare rectangular in cross-section having parallel top and bottom faces26, 27. The rearward ends 28 of the prongs 24 are preferably transverseand vertical.

Tooth 11 is preferably formed of a hard, tough material which willresist the abrasion of the digging action of the equipment with which itis employed. As one edge of the blunt end 18 is worn, the tooth ispreferably reversed until the entire distal portion is consumed.Further, if it is necessary to sharpen the end 18, this may beaccomplished by grinding. When the tooth is entirely consumed, it may bereplaced. The foregoing operations which are performed on the toothrequire that it be held on the digging equipment in a detachable mannerand yet that the tooth be securely restrained against unintentionaldisplacement.

A preferred form of tooth holder 12 is mounted on earth-diggingequipment or is integral therewith and in practice secures the tooth ina position as best shown in FIG. 2 slanted downwardly-forwardly foreffective digging action, it being understood that this particulararrangement is subject to wide variation.

Tooth holder 12 is formed with vertically spaced top and bottom portions31, 32, interconnected by a ver tical web 33, so that in front elevationholder 12 has an H-shape with the H turned on its side and providing apair of recesses 34 on either side of web 33 between portions 31 and 32.The inwardly facing top and bottom faces 36, 37 of recesses 34 arespaced apart the thickness of prongs 24 and the width of web 33 is equalto the distance between walls 23 of Slot 21, it being understood thatmanufacturing tolerances require slight clearances to permit insertionand removal of the tooth.

A resilient retainer 13 is employed. In the form of the invention hereshown, retainer 13 is round in cross-section and has a length greaterthan the thickness of web 33. A preferred material of construction isneoprene, a synthetic rubber, but it will be understood that otherresilient materials, such as natural rubber, nylon cord, latex dippedcord, iron wire, and other materials may be used.

In the form of the invention shown in FIGS. 1 t0 6, hole 41 extendstransversely through web 33 spaced backwardly a short distance from theforward end 42 of the web which normally engages the end 22 of slot 21.Longitudinal grooves 43 of extended length are formed on either sidewall 44 of web 33 rearwardly of hole 41. As best shown in FIG. 6, groove43 has a depth substantially less than the diameter of hole 41 and has awidth in a vertical direction substantially greater than said diameter41.

When tooth 11 is assembled in holder 12, as a preliminary step theinsert 13 is inserted through hole 41 so that it projects out into therecesses 34 on either side of web 33. Tooth 11 is then moved rearwardlyinto holder 12,- the prongs 24 fitting into the recesses 34. When therearward ends 28 of the prongs encounter the ex-- posed ends of theinsert 13 they force the insert rearwardly into the grooves 43. Byreason of the dimensions of the grooves 43 as compared with thecross-section of the insert 13, the insert is deformed into the shapebest indicated by reference numeral 46 in FIG. 6. Most importantly,there is an enlarged surface 47 of the insert in engagement with theside wall 23 of the slot 21 which frictionally engages wall 23 and moreeffectively prevents withdrawal of the tooth 11 from the holder 12 thanin prior constructions of this general type. However, openings 48 arepreferably formed in holder 12 rearwardly of the ends 23 of the tooth topermit a tool to be inserted and used to drive the tooth 11 forwardlyagainst the frictional restraint of the portions 46 of insert 13.

FIGS. 7 to 9, inclusive illustrate a modification of the invention.Because essentially the tooth and holder are similar to the form shownin FIGS. 1 to 6, the same reference numerals followed by subscript a areused to designate corresponding parts. Hole 41 of the modification ofFIGS. 1 to 6 is eliminated. In lieu of such a hole, four other holes 51to 54 are provided, it being understood that one or more of said holesmay be eliminated. Hole 51 is located extending through top portion 31a7 and into one of the recesses 34a immediately above the middle of oneof the prongs Zea adjacent the forward end of holder 12a. Hole 52 isidentical except that it is on the opposite side of the holder. Hole 53is located in bottom portion 32a in vertical alignment with hole 51 andhole 54 is in the corresponding position on the other side of the tooth.Grooves 56 to 59, inclusive, are

formed in holder 12a immediately rearwardly of holes 51 to 54,respectively. Groove 56 is formed in top face 36a of one of the receses34a immediately rearwardly of hole 51 in the direction of insertion oftooth 11a, and the other grooves are similarly located, it beingunderstood that when one or more of the holes 51 to 54 is eliminated itscorresponding groove is likewise eliminated. Each of the grooves 56 to59 is wide and shallow and bears the same relationship to the holes as,in the preceding modification, grooves 43 bear to holes 41.

For each hole 51 to 54 there is provided a resilient insert 61 to 64,respectively. Such inserts are placed in the corresponding holes priorto insertion of tooth 11a, and as the tooth 11a is driven into theholder 12a the inserts 61 to 64 are bent backward into the correspondinggrooves 56 to 59 and flattened, the deformed flattened portions of theinserts being indicated by reference numerals 66 to 69, respectively,Thus the inserts 61 to 64 function in a manner similar to the insert 13of the preceding modification to frictionally restrain unintentionallongitudinal displacement of tooth 11a from its holder 12a. It will beapparent that the tooth may be driven from its holder as by inserting aninstrument through knockout openings 48a, or other means as required.

The modifications shown in FIGS. to 12 are similar to those previouslydescribed, and parts similar to parts shown in FIGS. 1 to 6 aredesignated with the same reference numeral followed by the subscript b.In this form of the invention, horizontal, transverse holes 71 areformed in either prong 24!) adjacent rearward ends 28!) and locatedapproximately midway between top and bottom surfaces 26b, 27b of prongs24b. Grooves 72 are formed in side walls 44b of web 23b of holder 12b,extending forwardly from a point radially opposite the location of holes71 in the assembled positon of tooth and holder toward the forward end42!] of web 33b. The cross-sectional shape of groove 72 as compared withthe diameter of hole 71 is in approximately the same relationship as inthe preceding modifications. Resilient inserts 73 are positioned inholes 71 prior to assembly to the tooth and holder. As the tooth isforced into the holder the inserts fit into grooves 72 and are deformedand compressed to the shape indicated by reference numeral 74. Removalof the tooth for replacement is accomplished in a manner similar to theprevious modification.

Turning now to the modifications of FIGS. 13 to 1-6, the tooth 11c andholder 120 are generally similar to those of the preceding modificationswith exceptions hereinafter noted and the same reference numeralsfollowed by the subscript c are used to designate corresponding parts.In this modifications, vertical holes 76 are formed adjacent rearwardend 280 of one or more of the prongs 24c extending through from topsurface 26c to bottom surface 27c. Longitudinal grooves 77 are formed oneither side of top and bottom faces 36c, 370 of recesses 340 of holder12c. Said grooves extend from the front edge of holder 12c and terminateat a position approximately directly opposite the location of holes 76in the assemled positon of tooth and holder. The cross-sectional shapeof grooves 77 with relation to holes 76 is preferably the same as in thepreceding modifications. Resilient inserts 78 are installed in each ofthe holes 76 prior to insertion of the tooth and as the tooth is forcedinto its holder, said inserts bend into the grooves 77 and are deformedand compressed as indicated by reference numeral 79. Removal of thetooth is essentially as in the preceding modifications.

In the modification of FIGS. 19, 20, the tooth and holder are similar tothat shown in FIGS. 1 to 6 and the same reference numeral followed bythe subscript d is used to represent corresponding parts. This form ofthe invention is particularly suitable for large size teeth or teethwhich are subjected to extreme strain tending to separate the tooth fromits holder. This modification is 6 characterized by the use of aplurality of resilient inserts 13d, 14d instead of a single insert, thetwo cooperating and, by reason of the increased area of surfaceengagement, more effectively frictionally resisting disengagement.

Thus hole 41d is formed transversely through web 3311 adajcent theforward end 42d thereof and positioned in the lower half of sidewall44d. A second hole 40 is also formed transversely through web 33d in theupper half of sidewall 44d. Grooves 43d extend longitiudinally in eithersidewall 44d rearwardly of hole 41d. Groove 43d has the samecross-sectional relationship to hole 41a, as in the precedingmodifications. The assembled position of the tooth and holder resemblesthat in the preceding modifications, it being understood that insert 13ais deformed in portions 46d in grooves 43d, Whereas insert 81 isdeformed in portion 83. A second groove 82 is formed in side walls 44dof web 33d rearwardly of hole 40 and has a cross-sectional shape similarto groove 43d.

In the preferred form of the invention as herein shown, hole 40 islocated rearwardly of hole 41a in the direction of insertion of thetooth so that prongs 24d first engage resilient insert 13d and thenlater engage insert 81. This relationship makes it easier to insert thetooth in its holder because the resistance to insertion is not as greatas would be the case if the two holes were located the same distancefrom the front end of the holder.

The principle of using a plurality of resilient inserts instead of asingle insert is applicable to the modifications shown in FIGS. 7 to 9,10 to 12 and 13 to 16, as well as shown in FIGS. 17 to 20. One skilledin the art will understand that plural inserts may be used in place ofsingle inserts in these modifications, as well as in the modificationshereinafter explained in detail. In addition, various combinations ofthe locations of the inserts shown in the accompanying drawings may beused.

The modifications of the invention shown in FIGS. 21 to 24, inclusive,resemble the form of the invention shown in FIGS. 1 to 6, inclusive, andthe same reference numerals followed by subscript e are used todesignate corresponding parts. In this form of the invention, hole 41cextends through web 33c in the same location as in FIGS. 1 to 6.However, the grooves 43 in the side edges 44 of web 33 are eliminated.In this modification of the invention, longitudinal grooves 86 areformed in sidewalls 23a of slot 21c from the rearward end 28 forwardlyto a terminus approximately opposite hole 41s in the fully assembledposition of the tooth. Preferably, the dimensional relationship ofgroove 86 relative to hole 416 is about the same as in FIGS. 1 to 6. Itwill thus be seen that in this modification of the invention the meansof holding the tooth in its holder is essentially the same except thatthe grooves are formed in the tooth rather than in the toothholder.Although in FIGS. 1 to 6 the grooves are shown formed in the web, and inFIGS. 21 to 24 are shown formed in the tooth, nevertheless it will beclear to one skilled in this art that the grooves could be formedpartially in the tooth and partially in the holder.

In the modification of FIGS. 25 to 27, the tooth and holder resemblethose shown in FIGS. 7 to 9, and the same reference numerals are used todesignate corresponding parts following by the subscript 1 rather thanthe basic numeral, or the subscript a. In this form of the invention,grooves 56 to 59 in surfaces 36a, 37a are eliminated, although holes 51to 54 in portions 31 32] are formed. Grooves 87 are formed in the topand bottom surfaces 26 27 of each prong 24], extending longitudinallyfrom rearward ends 28 to a terminus approximately opposite holes Sle to54 Thus the resilient insert portions 66@ to 692 are located in thegrooves in the prongs rather than in the holder. In other respects, thefunctioning of the holder is essentially the same. It will further beunderstood that the grooves may be formed partially in the tooth andpartially in the holder, if desired, the construction being readilyapparent to one skilled in this art.

In the form of the invention shown in FIGS. 28 to 30, the tooth andholder resemble the form of the invention shown in FIGS. 13 to 16, inthat holes 76g are formed located vertically in prongs 24g. Thecorresponding parts are designated by the same reference numerals as inFIGS. 13 to 16, following by the subscript g. In this form of theinvention, grooves 77 in surfaces 360, 37c are eliminated. In lieuthereof, grooves 88 are formed in the top and bottom surfaces 26g, 27gof prongs 24g. The means of holding the tooth in its holder isessentially the same as in the preceding modification. Here again itwill be understood that the groove may be formed partially in the toothand partially in the holder if desired, as will readily occur to oneskilled in the art.

Although not illustrated herein, it will further be understood that theform of the invention of FIGS. 10 to 12 may also be modified byeliminating the grooves 72 in web 33b, substituting therefor grooves(not shown) in side walls 23 of tooth 11, extending forwardly from hole71 in a longitudinal direction.

Although the foregoing invention has been described in some detail, byway of illustration and example for purposes of clarity ofunderstanding, it is understood that certain changes and modificationsmay be practiced within the spirit of the invention and scope of theappended claims.

What is claimed is:

1. In combination in an earth-digging tool, a tooth portion formed of ahard piece of material with a tapered distal portion and a proximalportion, a holder portion formed with a recess to receive said proximalportion, one said portion formed with an aperture opening into saidrecess in the assembled position of said combination, one said portionformed with a groove communicating with said aperture and facing saidrecess, and a resilient insert partially in said aperture and partiallyin said groove and resiliently compressed in said recess between saidtooth and holder to frictionally restrain withdrawal of said tooth fromsaid recess, said groove having a depth substantially less than and awidth substantially greater than the initial, uncompressed thickness andwidth, respectively, of said insert whereby the cross-sectional shape ofsaid insert is substantially deformed as compared with its uncompressedshape and the area of surface contact between said insert and saidportions is greatly enlarged.

2. The combination of claim 1, in which said aperture is formed in saidholder.

3. The combination of claim 1, in which said aperture is formed in saidtooth.

4. The combination of claim 1, in which said groove is formed in saidholder.

5. The combination of claim 1, in which said groove is formed in saidtooth.

6. The combination of claim 1, in which said insert is an elastomericmaterial.

7. The combination of claim 1, in which said insert is nylon cord.

8. The combination of claim 1, in which said insert is latex-dippednylon cord.

9. The combination of claim 1, in which a plurality of apertures andgrooves is formed in said portion, and a plurality of inserts provided,each said insert received in one said aperture and compressed in onesaid groove.

10. The combination of claim 9, in which one said insert is set backrelative to the other said insert in the direction of insertion of saidtooth portion in said holder portion.

11. In combination, a detachable tooth member, a tooth holder member,one of said members shaped with at least one recess having a first wall,said recess formed to receive at least a portion of the second of saidmembers, said second member having a second wall in close proximity tosaid first wall and moving substantially parallel to said first wall assaid second member portion is inserted in said recess in said firstmember, one said member formed with an aperture in its respective wallextending transverse to the direction of insertion of said tooth in saidholder, one said member formed with a groove in its respective wallcommunicating with said aperture extending parallel to the direction ofinsertion of said tooth in said holder, and a resilient insert partiallyin said aperture and partially compressed in said groove andfrictionally engaging the wall opposite said groove, the depth of saidgroove being substantially less than and the width of said groove beingsubstantially greater than the corresponding initial, uncompresseddimensions of said resilient insert, whereby the area of frictionalcontact between said insert and the wall opposite said groove ismaterially increased.

12. The combination of claim 11, in which both said aperture and saidgroove are formed in the same wall.

13. The combination of claim 11, in which said aperture is formed in oneof said walls and said groove in the other of said walls.

14. The combination of claim 11, in which said recess is formed in saidtooth holder member.

15. In combination, a tooth formed of a unitary, hard piece of material,a tooth holder having a forward end formed with at least one recessextending rearwardly of said forward end, said recess having a side wallfacing said recess, and top and bottom walls generally transverse tosaid side wall, said tooth and recess shaped so that said recessreceives a portion of said tooth, a resilient insert, means to retainsaid insert in position normally compressed between one said wall andsaid portion of said tooth to resiliently, frictionally, detachablyretain said tooth and holder together, one of said walls formed with agroove in which said insert is partially received, the depth of saidgroove being substantially less than, and the width of said groove beingsubstantially greater than, the initial, uncompressed thickness andwidth, respectively, of said insert.

16. In combination in an earth digging tool, a holder shaped to receivethe proximal end of a tooth, a tooth having its proximal end shaped tofit said holder, said tooth having a slot extending forwardly from theproximal end of said tooth to divide said proximal end into two discreteprongs, said holder formed with recesses each shaped to receive one ofsaid prongs and having a web between said recesses substantially fillingsaid slot, and a resilient insert carried by said holder and bearingagainst said tooth, one of the members of the group consisting of theholder and the tooth formed with a groove, said groove having a depthsubstantially less than, and a width substantially greater than, theinitial, uncompressed thickness and width, respectively, of said insert,said insert partially in said groove.

17. The combination of claim 16, in which said groove is formed in saidweb.

18. The combination of claim 17, in which an aperture is formed in saidweb immediately forward of said groove, said insert partially receivedin said aperture.

19. In combination, a tooth formed of a unitary, hard piece of materialand having a slot extending forwardly from the proximal end of saidtooth to divide said proximal end into two discrete prongs, a toothholder shaped to receive said prongs and having a web substantiallyfilling said slot, at least one said prong formed with an aperture, saidholder formed with a groove communicating with said aperture, and aresilient insert in said aperture and compressed in said groove andfrictionally restraining Withdrawal of said tooth from said holder.

20. The combination of claim 19, in which said aperture extendstransversely through said prong normal to said web and said groove isformed in said web.

21. The combination of claim 19, in which said aperture extendstransversely through said prong parallel to the height of the web andsaid groove is remote from said web.

22. In combination, a tooth formed of a unitary hard piece of materialand having a slot extending forwardly from its proximal end to dividesaid proximal end into two discrete prongs, a tooth holder shaped toreceive said prongs and having a Web substantially filling said slot,said web formed with a first and a second aperture transverse to saidslot, said web formed with a first and a second longitudinal grooverearward of said first and second apertures, respectively, and a firstand a second resilient insert, each said insert in one said aperture andcompressed in one said groove and resiliently restraining Withdrawal ofsaid tooth from said holder, said second aperture spaced rearward ofsaid first aperture in a longitudinal direction and one of saidapertures elevated re1ative to the other.

23. In combination, a tooth for earth digging equipment having asharpened main working part and a connecting part, a holder formed witha recess to receive said connecting part, at least one wall of saidrecess formed with a hole and also with a groove extending ReferencesCited UNITED STATES PATENTS 2,968,880 1/1961 Petersen 37-142 3,057,09110/1962 Petersen 37-442 ABRAHAM G. STONE, Primary Examiner.

ANTONIO F. GUIDA, A. E. KOPECKI,

Assistant Examiners.

15. IN COMBINATION, A TOOTH FORMED OF A UNITARY, HARD PIECE OF MATERIAL,A TOOTH HOLDER HAVING A FORWARD END FORMED WITH AT LEAST ONE RECESSEXTENDING REARWADLY OF SAID FORWARD END, SAID RECESS HAVING A SIDE WALLFACING SAID RECESS, AND TOP AND BOTTOM WALLS GENERALLY TRANSVERSE TOSAID SIDE WALL, SAID TOOTH AND RECESS SHAPED SO THAT SAID RECESSRECEIVES A PORTION OF SAID TOOTH, A RESILIENT INSERT, MEANS TO RETAINSAID INSERT IN POSITION NORMALLY COMPRESSED BETWEEN ONE SAID WALL ANDSAID PORTION OF SAID TOOTH TO RESILIENTLY, FRICTIONALLY, DETACHABLYRETAIN